Single winding saturable core impedance devices



Oct. 3, 1961 J. B. c A 3,003,102

SINGLE WINDING SATURABLE CORE IMPEDANCE DEVICES Filed July 5, 1956 3 Sheets-Sheet 1 Fig-l. 2

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fnventar' (lame .s E ficFerran 3 Sheets-Sheet 2 i esszr cuuzwr LOAD cmuwr f)? Mentor- James A ficf'er'r'an J. B. M FERRAN SINGLE WINDING SATURABLE CORE IMPEDANCE DEVICES Filed July 5, 1956 Oct. 3, 1961 I an a .2 AW W C C w m U! 6 I H 4? I n EU 4 o (.040 cueuwr-l M 4040 conenvr-z cueezzvr-Z .9 fnesf arm:

77/15 fitter/76y SINGLE WINDING SATURABLE CORE IMPEDANCE DEVICES Filed July 5. 1956 Oct. 3, 1961 J. B. MOFERRAN 3 Sheets-Shoot 3 llIlIl $ECO/V0 STAGE REMESU .PNWMK IQFHESU Q (Q Q F/RS'T STAGE 94 ll llII LOAD CURRENT RESET CURRENT RESET cu/iwE/vr II LOAD CURRENT RESET CURRENT [r7 vent or James 13 //c Fr'r'an M's 7% torney p 3,oajo2@f SINGLE .Av LE CORE nurnmmcnn crs This invention relates to saturablie core impedance devices of the type commonly refe rred to as magnetic amplifiers and, particularly, to such devices known as single winding magnetic amplifiers. l v

The application of magnetic arnplifiers been limited large s hw fi l i r f t ea r at volved and the resulting e'zipense thereof. Much and effort v ean e i h 1 imPIifY th a a t and makeitineirpensivewithout reducing the reliability. A umber" of single winding magnetic amplifier circuits, which utilize the magnetic core -rese principle have been developed for relatively low power work (below about 25 watts). The reset principle'is more fully described below inconnection with thecircui't description.

One such basic'circuit is described and claimedin the application of John D. Hmdn,'rr;,. Serial No. 588.349,-'

filed May 31, 1956, and assigned to the assignee of the present invention. The present invention is an improvement over the invention described and claimed in the Harnden application and therefore I do not claim anything shown or described in said Harnden application.

Although the circuitry conceived and disclosed by Harnden is generally basicin character, he does not specifically provide for certain; applications. For example, there is no direct provision for biasingthe amplifier and there is no direct provision for performing additiOn Sub traction or mixing of a number of control or signal voltages. amplifiers, difiiculty is bad in 'cascading' stages andin obtaining discriminator action. t 1

Accordingly, it is an object of this invention to provide a saturable core impedance device of 'the single winding magnetic amplifier type which may readily be used in push-pull or cascade. I

A further object of this invention is to provide a saturable core impedance deviceof the character set forth wherein addition, subtraction and mixinglof control voltages or signals may be readily carried out.

Another object of thisinvention is to provide single wherein dis provide a single winding saturable core impedance device 1 which may be utilized as a voltage and'frequency reference. I a

It is to'be particularly" understood that the magnetic amplifier devices referred to in this application may utilize separate volt-age sources to supply the main reactorsup ply voltage and the magnetic core reset vo'ltage. Thus, the circuits disclosed herein have the economyof appara tus which accompanies" operatingwith the various parts of. the circuit at the optimum voltage level.

Briefly statedin accordance with this invention, certain of the improvements in saturable core impedance devices set forth above are" accomplished by pr'ovidinga magnetic amplifier havinga singlef magn'etic cbreand a single winding in flux exchange relationship therewithand' providing a means for utilizing one or more separate voltagestors'upply'the" energy neces ary to" resetthe mag:

netic core and still another separate voltage to" supply the power forthe reactor. '[he'ntimbenofiveltagesuth In addition, as with all single winding magnetic l atented ocna, 1961 ce v 2 lized to supply the energy to reset the magnetic core and the particular manner in which they are applied and controlled determine the operation of the amplifier.

In order to provide a summing amplifier, a difierential amplifier or a mixing amplifier wherein alternating current voltages and direct current voltages may be mixed.

a plurality of reset voltages areapplied to a desired portion of the single main winding of the amplifier 7 The novelfeatures whichare believed to be characteristic of this invention are set forth with particularity in the appended claims. I This invention, however, both as to its organization and method. of operation together with further objects and advantages thereof may best be understood by reference to the following description taken in conjunction withtheaccompanying drawings inwhich:

FIGURE 1 diagrammatically illustrates a-sin'gle" sided self-saturating half wave circuit; a

7 FIGURE Zillirstrats atypical dynamic hysteresis tor a magneticcore material which is utilized in explaining the pririciples of operationof the present invention; I

FIGURES 3 and 4v diagrammatically illustrate single sjided selflsat urating half wavecircuits embodying the present invention with connections to provide circuit biasing, addition orlsubtraction of control signals, or to provide'mi'xing control signal voltages of direct current and alternatingcurrent; a r. a a I a 1 FIGURES 5, 6 andf7 illustrate push-pull versions of thesing'lewinding self-saturating halfwave circuits embcdyingthe present invention;

FIGURES san 9' i1lustrate d agrammatically cascaded gstagcsiof single winding magnetic amplifiers of this in-' vention. a x p t FIGURES, IQ and 11 illustrate single sided and full waveconnections respectively" of the single winding magnetic amplifier of the present invention which may be used asa' voltage and/or frequency reference. a

v In order toundeirstand the concepts of thepresentinvention reference should be'made to FIGURE 1 wherein a single winding self-saturating half wave magnetic plifier 10 which utilizes the reset principle of operation is diagrammatically illustrated. The magnetic amplifier 10 includes a single magnetic core 11 the main or; gate WindingIZ woundlon one legof the coreinfiux relationship therewi th and a saturating rectifier 13 connected in a series circuitwhic hfinclud es an electric load device 14 (connected between load terminals Hand 16). .As

trated this series circuit' is energized, by, a conventional; alternating Lcurrenttransfo'rmer 18 which has a primary. winding connected to ani alternating current vaua e; source and a secondary winding *20 connected to the input terminals zr a 22 0f the magnetic amplifier. If desired,"thefload impedance device 14 may also be connected between the main freact'ance' winding 12 and the saturat ing; rectifier 13 or between the upper input terminal 21 and the saturating rectifier 13.

The ortion of thej magnetic amplifier I far includes the f main'or power developing circuit. In

order to' provide'control'forthe magnetic amplifier-a reset circuit is necessary. 'Ihe components of this-cir cnit" will" be described first and then" an explanation of the term reset and the reset principle will be given in some detail.

The reset components include a reset impedance 23 connected between reset impedance terminals 24 and 25 and a reset rectifier 26. In order to render these components operative to reset the core, the reset impedance is connected in a series circuit which includes the main power winding 12 of the magnetic amplifier and the load device 14. This series circuit is connected between reset supply terminals 27 and 28 which are connected to receive a reset voltage E and the reset rectifier 26 connected directly in shunt with the reset supply terminals 27 and 28. The polarity of the reset rectifier is such that the reset supply voltage E will only cause current to flow through the main reactor Winding 12 in the direction. indicated by the arrow labelled reset current.

The circuit will operate without a reset rectifier as long as the reset voltage E does not exceed the main reactor supply-voltage. It is only essential that the current set up in the main winding 12 of the magnetic amplifier 10 due to the reset voltage supply, flow when the load current set up in this winding by the main reactor supply voltage is not flowing and that the reset current and load current flow in opposite directions or senses through the main winding 12. This relationship is assured by adjusting the relative polarity of the reset rectifier 26 and the saturating rectifier 13 as well as the relative phase relationships or polarities of the main reactor supply voltage and the reset voltage. It will be noted that the same function may be accomplished by placing the reset rectifier 26 in the series circuit which includes the reset impedance 23 in the proper sense as well as by placing it in shunt with the reset supply terminals as illustrated.

Considering a full cycle of operation of the circuit of FIGURE 1 and taking the situation where the main reactor supply terminal 21 is positive with respect to reactor supply terminal 22 and the upper reset supply voltage terminal 27 is positive with respect to the lower reset supply terminal 28. Current will not flow through the reset circuit due to the fact that the reset voltage B is shunted by the reset rectifier 26. However, the saturating rectifier 13 will conduct and therefore magnetizing current will flow through the main winding 12 of the magnetic amplifier 10 and the load impedance 14 in the direction indicated by the arrow labeled load current. As is explained more fully later, the magnetic amplifier 10 absorbs the entire volt-time integral from the voltage applied between its input terminals 21 and 22 until the core member 11 becomes saturated. Once the core member 11 is saturated load current flows in this series circuit and, consequently through the load device 14, during the remainder ofthis half cycle of the supply voltage. During the next half cycle of supply voltage (and reset voltage) the lower supply terminal 22 and the lower reset supply terminal 28 are both positive with respect to their upper terminals 21 and 27, respectively. Thus during this half cycle current flows through the reset circuit which includes load device 14, main reactor winding 12 and reset impedance 23 in the direction indicated by the arrowv labeled reset current. This reset current flows through the main winding 12 in a direction which is opposite to the load current and therefore acts to drive the reactor flux away from positive saturation. The magnitude of the reset flux thus established is determined by the magnitude of the reset impedance 23 and the reset voltage E As stated above, the value of the reset impedance 23 and the reset voltage E, determines the core reset flux setup by the main power winding and therefore determines the amplification of the circuit. In order to understand the action of the flux reset principle more clearly reference should be made to FIGURE 2 of the drawing which illustrates the dynamic hysteresis loop of a typical ferromagnetic material which might be used in the core 11 of the magnetic amplifier 10 illustrated in FIGURE 1.

Cil

The dynamic hysteresis loop represents a plot of flux density B in the core 11 against the external magnet z ng force H applied to the core when the applied magnetizing force is varied at a finite speed. The finite speed at which I the magnetizing force is varied to obtain the dynamic hysteresis loop being considered is the frequency of the reactor power supply. The area enclosed by the loop is a measure of thecore losses of the material at the operating frequency when the operation of the circuit takes place around the major loop. The energy necessary to supply the core losses must be applied to the core 11 before it becomes saturated and permits load current to flow in the main winding 12. The points +8 and S respectively represent positive and negative saturation of the core material.

Assume that the current in the main winding 12 on the core 11 is such that the core is operated on its major loop. For this condition, it is necessary to supply sufiicient energy to the main winding 12 to supply the energy represented by the area of the loop before current will flow (current other than magnetizing current) in the load device 14.

The operation of the circuit may best be understood assuming first that the reset impedance 23 is so large that no current can flow through the reset circuit. For this condition, the load current is the only current which will flow in the main winding 12. As a consequence, the core 11 is not reset on the non-conducting half cycle and the operation of the apparatus is as follows: Assuming that the upper main reactor input terminal 21 is positive with respect to the lower input terminal 22 and the core is at some point past positive saturation +S, as the alternating current voltage supplied between the terminals 21 and 22 reduces to zero the current in the main Winding 12, also passes through zero and the applied magnetizing force becomes zero. However, the flux density therein remains at the point 30 on the saturation curve since there is no leakage current through the saturating rectifier 13. Since no current flows in the main winding 12 during the negativehalf cycle of the supply voltage, there is no demagnetizing energy supplied to the core. Therefore, the fiux density in the core cannot be driven below the point 30. Thus on the next positive half cycle of the supply, very little magnetizing force (energy) is required to drive the core to positive saturation, the impedance of the magnetic amplifier 10 is a minimum, and thecurrent conducted by this winding is a maximum. Since the energy used in supplying core losses is a minimum, the power supplied to the load device 14 is a maximum.

For the opposite limiting condition, i.e., with the ma gnitude of the reset impedance 23 very small, a maximum currentfiows through the reset circuit for the reset (negative) half cycle of the supply voltage. Once again, starting the explanation for the time when the supply voltage is passing through Zero (from positive to negative), there is no magnetizing force applied to the core 11 at this instant and the flux density in the core is again at the point 30 on the saturation curve of FIGURE 2. Reset current then starts to flowthrough the main winding 12 in the opposite direction or sense to that which flowed during the positive half cycle. The demagnetizing energy thus supplied drives the flux density of the core material down along the back side of the hysteresis loop until the core 11 reaches negative saturation S at the maximum reset voltage. As the alternating supply voltage reverses, the magnitude of the reset voltage and, consequently, the magnetizing force applied to the core 11 by the main winding 12 is reduced to zero, the core is reset, and the point of operation for the core is at 31 (i.e., at the magnetizing force axis and at the maximum negative flux density), In order to develop an output voltage across the load device 14 on the next (positive) half cycle of the reactor supply voltage, it is necessary to supplysufiicient energy to the core to drive the flux density of the core material to positive saturation +S (up along the front aware;

sideor hysteresis loop rrompeimsr wipes-reissue; when): nuswhenthe'ampufier 10' is operatm iiimanner; igeL; the magnitude of thereset im edaace zsis at a minimum, theoutput isat'a minimumwhe'reas-op erationof the device with zero reset'current provides a maximum output.

By varying the magnitude of the reset impedance {23; or the magnitude of the'reset voltage E or'bo'thj-"i is'pb i ble to set the operation of the magnetic amplifier 'at anypoint between the two points of operation justdeser'ih I For example, if the impedance such that the reset current is sufiicient to set the point of operation at "the" point 32 on the back side of the hysteresis lo'op, then on" the next positive half cycle of the reactorsupply voltage, it will be necessary to supply sufiicient energy to the core 11 to drive the core material up along the minor hysteresis loop illustrated by the broken line M within the dynamic hysteresis loop"=D. The energy-required to perform this is fsomewherebetween that required to drive the core to saturation +8 for the two limiting conditions. i

From the above description, it will be appreciated that the core is reset on each reset half cycle and, therefore; the amplifierprovides half-cycle response. it is'al'so seen that the reset ampere turns (i.e., the reset current times the number of turns on the main winding 1'2) required to swing the output of the amplifier over itsentirecharacteristic is approximately or essentially the same as the ampere turns required to swing the saturable core'impedance device over its full characteristic as a conventional magnetic amplifier. Since the core is driven into saturation. during the forward or fconducting" portion of each cycle its degree of reset is completely dependent on the previous half cycle, hence half cycle response is obtained.

The variable reset impedance 23may take many forms and its impedance may be'selected so that its magnitude varies in rmponse to any desired parameter. The proper control parameter is then usedto control the magnitude of'the' reset impedance used, to thereby control the system currentfvoltage is applied it should be of opposite polarity to the forward conducting sense of the supply voltage.

As is explained more fully below, the circuit of FIG- URE 3 may be utilized for addition and subtraction of control signals and for nnxingcontrol voltages of signals.

The principle of operation of this circuit is essentially the same asthat described with regard tdFIGURE l, amine components are generally the same. Therefore, in' order to simplify the'description, the corresponding components ofthe two circuits are given thesame 'rereren'cjenumerals. Thed-ifferenee between the two'circuits' 'asillustrated, resides entirely in the resetarran'gement-the main pawei circuits are identical. g g

In the circuit of FIGURES three individualser'ies' reset circuits are provided, each of which inc1udes"themainreactor winding 12 and a reset rectifier 29; One such series reset circuit" may betraced from reset voltage" tierminal 33., through variable reset impedance 34; reset rectiher 29, main reactor winding 12, and load device 14to lower reset voltage terminal 35. If a resetvoltage Em is applied between the reset voltage terminals 33 and 35 which isof the same frequency and phase as the main re actor supply voltage applied between supplyterniinals 21 and 22, the circuit described thus fa'r operates in exactly thesame manner asthe circuitof FIGURE 1. The-only difference betweenthe two circuits being that the reset rectifier illustrated in FIGUREZ is connected inseries rather than in shunt with the reset circuit. Howeventhe seriesreset rectifier operates in the samemarinef in that it allows resetcurrent to'flo'wonly in" the proper direci tion-'(illustr ated'by thearrow labeled Reset Current). Actually the"reset rectifier 29* maybe connected in shunt or it eybeelniifnated entirely if the total applied voltage never main 3 reactor voltage;

In order'to provide a summing or differentialamplifier' a number of additional reset circ'uits' must be'providedl As illustrated, resetimpedances 36 and37 are each-con nected between individual reset voltage terminals 38 arid 39 respectively, and the saturating rectifier in such a man net-that they are'in'each series circuit relationship with the fsatflrating're'ctifier29,*main winding 12. and load "de' vice 14. The individual reset voltages E and E 3 for each of these two reset circuitsis then applied between the lower" reset voltage terminal 35 and their respective upper reset' 'voltageterminals and 39.

this arrangement; the net reset current through the main reactor winding 12 'will'be a'function of the algebraic sum'of the control parameters -applicd if the ap: plied reset voltages Em,-"E ,and E i; are varied inaccio'rdance with a desired control parameter or if both the ap-' plied voltages and themagnitude of the reset impedances are so varied. Thus, the amplifier is itself a summing or differential amplifier. It will also be noted that asimilar relationship f applies if themagnitude of the reset irn-' pedances 34, 36, and 37 are varied in accordance with i11 dividual control parameters. 7 v

Provision of the-additionalreset circuits also adapts the amplifier for use as a mixingamplifier to combine alternating-andfiirect current signals. This function'is accomplished by the expedient of applying an alternating current voltage-to'one or more of the reset circuits and a direct currentvolt'age to the remainder of the reset circuits.

The circuitof FIGURE 4isincluded to illustrate a circuit wherein the point of operation of the core member 11 may. be set at some pointother thanthe' point'of zero magnetizingforce (pOintSM-FIGURE 2) by a biasing air: cuit. This circuit also illustrates a means of providing a means of-matching the impedances of the reactor and variouscontrol'signal voltage sources; This impedance matching permits "voltages rm; sources of different im' pedance levelsto be combined. p I

The principleof operation of the rnainfreactor circuit andt he reset circuits illustrated in FIGURE'4 are identical to those of "FIGURE 3 and corresponding 'circuit elements of the two circuitsQare given the samererereaee numerals: However, forthe' circuit of FIGURE 4 it is assumed that t h'e'reset voltage'sources E E paudEm have different impedances'; Therefore, in order to match these impedances so that the'individual voltage sr'mrces' will'haveidentic'al' efiects on the' main reactor circuit for a given applied reset voltage; it is necessary to include adifferent percentage of the main winding in each series circuit. Thisis' done by'providing a series of taps/on the 'mainreactance windingto which the individual'reset circuits may be connected. 'For example, one reset .jcircuit includes upper reset voltage terminal 39; reset impedance 37, reset rectifier 40, aboutrninety percentof the main reactor winding 12;, load device 14 and lower reset, voltage terminal 35 The reset circuit connected between reset voltage terminals 35 and JSfinclude's' resetimpedance '36, reset rectifier 41, about fifty pereent of" the main reactor winding 12, and load device 14; The third series reset circuit is connected between reset voltage terminals 35 and 33 and includes: reset impedance 34, reset rectifier 41, about ten percent ofthe main reactor winding '12, and the load device 14." The three/reset rectifiers40 f4l} and 42 re e ' blogk current in their respective reset circuits, which would flow in the wrong direction did resetrectificr 29 'in the circuit of FIGURE '3. As was previously explained, it is not necessary to include "the reset rectifiers if the. applied reset voltages are'nevergreater than themain reactor voltage. p g V In order to provide biasing the amplifier a biasing voltageE is' applied toj'about "fifty percent of the reactor winding 12. fIhis voltage provides an initial magnetizing force and thereby sets the operation of the core at some pdinton its dynamic hysteresis loop whichis other than the point of zero magnetization (point 30 of FIG- URE 2). For example, the initial magnetizing force may be such as to set the point of operation on the back side of the hysteresis loop at some point such as point 32 of FIGURE 2. Under these conditions, any reset voltage applied to the core drives the core further down the back side of its hysteresis loop. The reactor power supply voltage then must supply more power to drive the reactor to positive saturation +S than would be required without the bias. Therefore, the amplifier fires later in the cycle with a bias of the type described.

For the condition described above the biasing voltage E applied between the terminals 7 and 22 is polarized to apply a negative voltage at the terminal 7 at least during the reset half cycle of supply voltage. If the biasing volt age is reversed, i.e., arranged to apply a'positive voltage to the upper terminal 7 during at least the reset half cycle, it could provide a magnetizing force which would tend to hold the core member 11 at positive saturation and larger reset voltages would be required to reset the core.

The biasing circuit illustrated includes biasing resistor 6, the lower half of main reactor winding 12, and load device 14. The biasing E voltage is applied between the biasing terminal 7 and the lower load terminal 16. The biasing voltage E may, of course, be an alternating current voltage or direct current voltage.

As was explained with regard to the circuit of FIGURE 1, the specific location of the load device 14 in the main reactor circuits of FIGURES 3 and 4 is not critical. For example, in either the circuit of FIGURE 3 or the circuit of FIGURE 4 load device 14 may be connected between the main reactor winding 12 and the saturating rectifier 13 or between the upper input terminal and the saturating rectifier 13 without affecting the circuit operation appreciably.

In the circuit of FIGURE 5, a push-pull arrangement of two single winding magnetic amplifiers is shown. It will be recognized that the main reactor circuit for each of these single winding devices is identical to the main reactor circuits of the amplifiers already described. However, to avoid duplication of reference numerals in a single figure, components of this circuit are given new reference numerals.

The main reactor circuit of the first amplifier is connected between the two upper reactor supply voltage terminals 43 and 44 and includes saturating rectifier 45, main reactor winding 46, and load device 14 (connected between load terminals 15 and 16). The main reactor winding 46 is wound on a magnetic core member 47.

A transformer 48 which has a primary winding 49 connected to receive an alternating current voltage and a center tapped secondary winding is provided to supply the main reactor voltage. For this purpose, the upper half of the tapped secondary winding 50 is connected between the reactor voltage supply terminals 43 and 44. With this arrangement load current flows through this circuit only for the half cycle of supply voltage when the upper supply terminal 43 is positive and only in the direction indicated by the arrow labeled Load Current. This condition is established by the polarity of the saturating rectifier 45. a

In orderto reset the core member 47 a series reset circuit is provided which includes a reset impedance 51, a reset rectifier 52, and the main reactance winding 46 connected in series with each other between reset voltage terminals 53 and 54. A reset voltage supply is then connected between these terminals. Preferably, the reset voltage is of the same frequency and phase as the main reactor supply voltage. The portion of the push-pull circuit of FIGURE described thus far constitutes a single winding magnetic amplifier which operates in exactly the same manner as the single sided single winding magnetic amplifier of FIGURE 1.

In order to provide push-pull operation another single winding amplifier is also connected to supply the load device 14. The main reactor circuit of this amplifier may be traced from the middle reactor supply terminal 44, through load device 14, through a main reactor winding 55 of the second single winding amplifier, and through a saturating rectifier 56 to a lower reactor supply terminal 57. The main reactor winding 55 is also wound on a magnetic core member 58. The lower half of the secondary winding 50 of the transformer 48 is connected between the reactor terminals 44 and 57 to supply the reactor voltage for the lower half of the push-pull amplifier combination and the saturating rectifier 56 is poled to pass current through this circuit only when the upper reactor terminal 44 is positive with respect to the lower terminal 57. Thus, the load current tends to flow through the lower main reactor circuit only on the same half cycle that it flows in the upper main reactor circuit. Under these conditions, the load currents tend to flow in opposite directions through the load device 14 and at the same time (see arrows labeled Load Current-1 and Load Current2). Therefore, no load current will flow if the circuit is balanced and both core members 47 and 58 are reset by the same amount.

The core member 58 of the lower half of the push-pull amplifier is reset by a circuit which includes a reset impedance 59, a reset rectifier 60, and the lower main reactance winding 55 connected in series with each other across the reset supply terminals 53 and 54. It will be noted that if this lower single winding magnetic amplifier were isolated from the upper one, its operation would be exactly the same as described with respect to the circuit of FIGURE 1.

As previously noted, the load current developed by each half of the push-pull magnetic amplifier tends to flow through the load device 14 in opposite directions and therefore if the circuit is completely balanced and each of the core members 47 and 58 are reset by exactly the same amount on the reset half cycle, the current developed by each half of the magnetic amplifier will cancel out and there will be no current flowing through the load device 14. However, if an alternating reset voltage is applied between the reset terminals 53 and 54 the current flowing through the load device 14 on conducting half cycles is polarized in accordance with the phase of the alternating current signal. This action is insured by the polarity of the saturating rectifiers 45 and 56 and the reset rectifiers 52 and 60. In a like manner, the load current will be polarized in accord with the polarity of a direct current signal voltage if such a voltage is applied between the reset voltage supply terminals 53 and 54. This implies descriminator action as well as pushpull amplification.

For example, for the condition where the upper terminal 43 of the upper half of the push-pull amplifier is positive with respect to the middle terminal 44 and consequently the middle terminal 44 is positive with respect to the lower terminal 57 and for the condition where an alternating current reset voltage is applied between the reset terminals 53 and 54 in such a manner that the terminal 54 is positive with respect to the terminal 53 for this half-cycle of supply voltage, the load current in the upper half of the push-pull magnetic amplifier will tend to flow in a clock-wise direction around the loop as illustrated by the arrow labeled Load Current-1" and the load current in the lower half of the push-pull magnetic amplifier will tend to flow in a clockwise direction as indicated by the arrow labeled Load Current-2. At the same time the reset current for the upper half of the magnetic amplifier will be blocked by the reset rectifier 52 whereas reset current will tend to fiow in the lower series reset circuit. Whether or not this reset current can flow during this half cycle will depend upon whether or not the reset voltage applied is of sufficient magnitude to oppose the voltage developed across the main reactance winding 55 of the lower half of the push-pull magnetic subarea '9? amplifier. Generally; this re etstatesmanbei norea duringtheconductinghalfcyclei g I on the next half cyclefthe middle" terminal 44' is posi tive'with respect to the upper terminal 43 and the lower terminal 57 will be positivewith" respeet to'the middle terminal 44, therefore, load current cannot flow in either of the reactive circuitsdue to the fact that it is blocked by the saturating rectifiers 45 and 56. However, it is during this half cycle'that the reset of the cores 47 and 58 must take place. During this'half cycle the left hand reset voltage supply terminal 53 is positive with respect to the right hand reset voltage supply terminal 54. For this condition reset current will tend to fiow throughthe' upper main reactance winding 46 due to the fact that the reset rectifier in this reset circuit ispro'perly poled. The reset current through the lower'main reactance winding I 55 is blocked due to the polarity of the reset rectifier 60 not reset at all and, therefore, the'loaid current, i.e., the

current through the load device 14, will be predominantly in the direction of the arrow labeled Load Current2. Anotherway of stating this is to say that the lower half of the push-pull magnetic amplifier circuit will require less magnetizing force to cause current to flow therein due to the fact that the magnetic core member 58 of this circuit is not reset. 7 r

In a like'manner if the polarity of the reset voltage applied between the reset supply voltage terminals 53 and 54 is reversed so that the terminal 53 is positive when the upper and middle reactance supply voltage'terminals 43 and 44 respectively are positive with respect to the lower reactance voltage, supply terminal 57, the lower core member 58 will be fully reset on the reset half cycles and the upper core member 47 will not'be reset. Therefore, thecurrent through the load device 14 will be polarized in the direction opposite to that described above, i.e. it will be predominantlyin thedirection of the arrow labeled Load Current-l. It will be recognized then, that the relative degree of reset of the upper and lower magnetic core members 47 and 58 maybe varied between these conditions by the varying phase ofthe'applied reset voltage between the two extremes just described. It should be equally apparent that the two extreme conditionsdescribed above also-prevail if direct current reset voltages of opposite polarity are applied between the reset voltage terminals 53 and 54.

It will also be understood that fora reset voltage of a given phase, the degree of reset of the'cores may be varied by varying "the magnitudeof the resetvoltage or byvarying the magnitude of the reset impedances 51 and 59. Therefore; for thepush-pull circuit of FIGURE 5, control of the load current or voltage developed across the load may be accomplishedby varying the magnitude of the reset voltage, the phase of the reset voltage, or the magnitude of the reset'impedances 51 and 59, or any combination. of these parameters may be'varied as desired.

The push-pull circuit of FIGURE may be modified in all respects set forth with'regardto the single-sided amplifier circuits previously described by modifying both the upper and the lower halves of the push-pull circuit in the sam e manner; Forexample', the push-pull". circuit may be made a sumrning'amplifier, a differential amplifier or a mixing amplifier, and the single winding halves of the push-pull magnetic amplifier maybe biased. The

circuit illustrated in FIGURE 6 shows a push-pull mag identical to the corresponding reset circuits illustrated in FIGURE 5 with the exception" that theresetvoltage is applied in such a manner that the reset circuits for both the upper and lower halves of the push-pull circuit include load device 14. Since the corresponding components 'of' this portion of the circuit of FIGURE 6*are identical to the corresponding components of the circuit of FIG-' URE 5 they are given the same reference numerals for the sake of simplicity. I

Also since the operation of this portion of the circuit illustratedin FIGURE 6 is identical to the operation of the circuit of FIGURE 5, the operation ofthispart of the circuit will not be described again However, in addition to the first reset circuits which include the reset impedances 51 and 59 and-thereset rectifiers 52 and 60, a second reset circuit is added for each half of the pushpull amplifier circuit. The second reset circuit for the upper halfof the amplifier which may be traced from the right hand reset voltage terminal 61 through reset imped} ance 62, saturating rectifier 52 main reactance winding 46, loadimpedance device 14, to input terminal 44 and back to the left handreset voltageterminal 63. The second reset circuit for the lower half of the push-pull magnetic amplifier circuit may be traced from the right hand reset voltage terminal 61 through reset impedance 64, reset rectifier 60, the lower main reactance winding 55, load device 14, reactance voltage supply terminal 44 and back to the left hand reset voltage supply terminal 63. A second reset voltage is then applied between the reset voltage terminals 61 and 63.

With the circuit as described thus far it will be seen that an alternating voltage supplied between the reset voltage terminals 61 and 63 which is of the same frequencyas the main reactance supply voltage will have the same efiect as that described with respect to the first reset circuit of the. push-pull magnetic amplifier illustrated in FIGURE 5. However, it be appreciated that the reset control applied between the two pairs of voltage supply terminals will not .be independent and that they can be mixed in any manner desired. The net effect on the reset of the individual saturable core devices 47 and 58 will represent the algebraic sum of the effect of individual reset circuit which acts upon the respective core members. Therefore, it will be appreciated that the relative phases of the individual reset voltages, the magnitudes of thereset impedances in the reset circuits, and the magnitudes of the applied reset voltages may all be varied to accomplishe controlof thepush-pull amplifier. also be recognized'that one of the reset voltages may be direct current and the other alternating current having the same frequency as the main reactor supply voltage and I in this manner mixing of alternating current and direct current voltages may be obtained.

, In addition to the circuitry thus far described and illustrated in FIGURE 6 biasing of the amplifier may be ac complished by connecting the opposite end terminals of a center tapped secondary winding'65 of a transformer 66 across the reset impedances'62'and 64 of the last reset circuit and connecting the center tap to the main reactor input terminal 44 which is connected to the center tap-on the secondary winding 50 of the reactance supply trans former 48u The primary winding 67 of the transformer 66' is connected to a voltage source of the same frequency as the main reactorlsupply voltage. The relative phases of'the two transformer voltages determines which way the amplifier is biased. Since the biasing circuit for each half of thepush-pull amplifierar'ran'gement includes the respective reset rectifiers 52 add the biasing circuitsare much the sanfie"a.-ifthe reset circuits" already traced. Therefore; it will be understood that for one polarity'of the biasing voltage on thejsecondaryl65 of trarisformer'66with respectto the main reactor voltages,

It will the biasing voltage will be applied to the upper main reactance winding 46 and for the opposite relative phases of these two voltages the biasing voltage will be applied to the main reactance winding 55 of the lower half of the push-pull circuit. Biasing of a given core has been adequately explained with respect to the circuit of FIGURE 4 and therefore is not explained again at this point.

Still another push-pull circuit arrangement utilizing the single winding magnetic amplifier is illustrated in FIG- URE 7. Since the circuit components are rearranged somewhat from those corresponding components illustrated in FIGURES and 6, the circuit components will be given dififerent numbers to avoid confusion. The upper main reactance circuit of this push-pull magnetic amplifier includes an upper reactance input voltage terminal 70, a main reactance winding 71 wound on a magnetic core member 72, saturating rectifier 73, a load device 14 connected between load terminals and 16, and main reactance voltage input terminal 74. These components are connected in series with each other across the upper half of the secondary winding 75 of a transformer 76 which has its primary winding 77 connected to receive an alternating current voltage. The saturating rectifier 73 is poled in such a manner that the load current in this upper main reactance winding 71 flows in the circuit in a clock-wise direction as indicated by the arrow labeled Load Current-1.

In order to provide a reset for the magnetic core member 72 a reset circuit is provided which may be traced from a voltage input terminal 78 through reset impedance 79, reset rectifier 80, main reactor winding 71, through the upper half of the secondary winding 75 of the reactance supply transformer 76 to the reactor input terminal 7 4 and back through the left hand reset voltage input terminal 81. It will be recognized that the single winding magnetic amplifier described thus far will operate in a manner similar to the single sided magnetic amplifier of FIGURE 1 with the exception that the reset circuit includes a portion of the main reactance supply voltage. Thus, the reset voltage applied to this circuit is the algebraic sum of the voltage applied between main reactor voltage supply terminals 70 and 74 during the reset half cycle and the reset voltage applied between the reset voltage supply terminals 78 and 81 during this half cycle.

The lower main reactance circuit of the push-pull magnetic amplifier circuit consists of a lower main reactance winding 82 which is wound on the magnetic core member 83, a saturating rectifier 84, and the load device 14, connected in series with each other between the middle react-ance voltage supply terminal 74 and the lower reactance supply terminal 85. This series circuit is connected to receive the voltage developed across the lower half of the secondary winding 75 of the reactor supply transformer 76.

The reset circuit for the lower half of the push-pull magnetic amplifier consists of reset impedance 86, reset rectifier 87, the lower main reactance winding 82, lower half of the secondary Winding 75 of transformer 76, and the middle reactance voltage input terminal 74. These components are connected in series circuit relationship with each other between the reset voltage supply terminals 81 and 78. Without the upper half of the pushpull circuit it will be appreciated that the lower half will operate in substantially the same manner as described with respect to the single sided circuit of FIGURE 1, except that the reset voltage for this circuit comprises both the voltage applied between the reset voltage supply terminals 78 and 81 and the voltage applied between the lower pair of reactor supply voltage terminals 74 and 85 on the reset half cycle.

The load current in each of the main reactor circuits tends to flow in a clock-wise direction as illustrated by the arrows marked Load Current and as a consequence if the upper and lower reactor circuits are perfectly balanced and the cores 72 and 83 are reset on each reset half cycle by the same amount, no current flows through load device 14. In view of the polarity of the saturating rectifiers 73 and 84 it will be recognized that the reset current flowing in either of the main reactor windings 71 or 82 must flow during the half cycle of the main reactor supply voltage when the lower main reactor voltage supply terminal 85 is negative with respect to the middle reactor supply terminal 74 and when the middle reactor supply terminal 74 is positive with respect to the upper reactor supply terminal 70. If the reset voltage is applied in such a manner that the right reset voltage supply terminal 78 is positive for the reset half cycle of supply voltage, the reset voltage aids reset current flow through the upper main reactance winding 71 and opposes current flow through the lower main reactance winding 82. Consequently the upper reactor core 72 resets more than the lower reactor core 82 and therefore current through the load device 14 is polarized in the direction maintained by the lower reactor circuit, i.e., from left to right through the load device 14.

If the polarity of the reset voltage is reversed for the reset half cycle of supply voltage, i.e., reset supply voltage terminal 81 is made positive with respect to terminal 78, reset current flow is aided in the lower reset circuit and opposed in the upper reset circuit. Thus, the above described condition is reversed and the current through load device 14 for this condition is primarily supplied by the upper reactance circuit. As a consequence, load current flows from right to left through the load device 14.

From this description it is seen that this push-pull circuit operates in a manner similar to that described with respect to the circuit illustrated and described with regard to FIGURE 5. In this connection it should be noted that the modifications applied in the circuit of FIGURE 6 to make the push-pull circuit a summing or differential amplifier, for the purpose of mixing alternating current and direct current signals, or for applying a biasing voltage can also be applied equally well to the circuit of FIGURE 7 by connecting additional reset circuits in parallel with the reset circuits shown and by connecting a biasing circuit in the manner illustrated with regard to FIGURE 6. Also from the above description it is seen that the circuit of FIGURE 7 operates as a discriminator since its output may be polarized in accordance with either the phase of an alternating signal voltage or the polarity of a direct current signal voltage.

The circuit diagram of FIGURE 8 illustrates one arrangement whereby more than one stage of amplification may be realized using single winding magnetic amplifiers. Although the principle of operation of each stage of the two stage magnetic amplifier is the same as the circuit of FIGURE 1, it has been necessary to make certain modifications in the circuitry of the first stage in order to provide the two stages of amplification.

As illustrated, the two stage magnetic amplifier voltage source comprises an alternating current transformer 99 which has a primary winding 91 connected to an alternating current voltage source and a secondary winding 92 which is connected to a pair of main reactor supply terminals 93 and 94. The first amplifier stage is provided with a reactor having a single main conducting winding 95 wound on a magnetic core member 96 and the second stage of amplification is provided with a reactor which has a single main conducting winding 97 wound on a magnetic core member 98. The main reactor circuit for the first amplifier stage is connected between the reactor voltage supply terminals 93 and 94 and includes saturating rectifier 99, the main reactor winding 95, a reset impedance for the second amplifier stage, the main reactance winding 97 of the second stage, and load device 14 which is connected between load terminals 15 and 16. The second stage reset impedance 1%, second stage main reactance windtherefore the corresponding components .cuits are givenlike reference numbers.

vided'which may be tracedfromfan upper reset v'oim e supply terminal '101 through a first stage reset impedance 102, a reset rectifier 103, the main reactance-Winding 95 of'the first amplifier stage; and an'iso'lating rectifier 104' back to the lower main re'act'ance voltage supply terminal 94.- With this arrangement" it may beseen that.

on the forward or con'ducti ngh'alf cycle for thefirst amplifier stage the load curren't news" down through the main reactancewindin'g" 9S as indicated by the arr'otv labeled Load Current" andth'at the current infthe series res'etfcircuit just" described is blocked T by reset rectifier 103 and isolating' rectifier 104-. On the opposite half cycle of the supply"voltagejthe'reset current flows upwardly through" themain rea'cta'r'rce winding 93 as indicated bythe arrow labeled"Reset Current. Thus, if the second stage reset"impedance100, second'stage main reactance 1 winding 97' and the load device 14*are considered to be the load1for' the first stage" magnetic amplifierthen this stage will operate'in' the same manner andon {the same principleas did the magneticarnplifier of'FIGURE 1.

The main reactance'circuitfor the second'stage'magnetic amplifier may be'traced from the lower're'a'ctance supply voltage terminal 94 through the load'device 14, the main reactance windin'g'91, and through'th'e second stage saturating rectifier 105 back to'the upper-reactance supply voltage terminal 93. Thepolarity of the second stage saturating rectifier 105 is such that the direction of. load current fiow inthe secondstage magneticamplifier must be' up through the main reactance winding 97 'inthe direction indicated by the arrow labeled"Load Current. Thus the first and second stage-,magnetic amplifiers conduct on'alternate half cycles Ofithemain reactance supply voltagei' In view of this factit will be understood that the current which flows down through the second stage main reactance winding 97 (in'the direction shown by the arrow labeled Reset Current) due to' the conduction throughthe first stage main reactancewiridirig95; acts to provide reset for the second stage magnetic core member 98-and thereby determines the degree of reset of this corememb er; As a consequence a first stage main reactance winding-95' which has a relatively-large number of turns andpr'ovides a low power output may be used to control the reset and consequently the conduction of the second stage magnetic amplifier which may be arelatively high power device. For example; suchan arrangement utilizing the two stages may bereadily used to supply a watt load.

It will be readily appreciatedthat the stages otarnplification may be modified as suggested with regard to any of the single sided magnetic amplifier circuits illustrated herein. It should also benoted that the isolating rectifier104 is only provided to prevent undesired feed back between stages and operation is possible without it.

As was pointed out with respect to the previous singl'e sided-magnetic amplifiers discussed, theload device l t may be placed between the second stage saturatingflre'etifier 105 and thesecond stage main reactor winding 97 or it-may be connected in thelead between the second stage saturating rectifier 105 and'the' firs't' stage saturating rectifier99 without appreciablyafiecting'operation of-the amplifier. V

7 Another circuit wherein stages of single winding magnetic amplifiers may be cascaded is"provided asillustrated diagrammatically in FIGU'RE9J W This arrangement includes the same components described with respect to the circuit FIGURE Sj'and inthc'twocir i w r; th circuitryin the second stage of the magnetic'amplifier illustrated in FIGURE 9 is arranged to preventattenuation of the reset signal from the first amplifier stageby be traced from the upper reactance supply voltage terfii siisa the d stage saturafih reetifier 105.

the problem of using taps in thesecond stage rnain' reactor winding'97 to allow impedance matching" between the second stage reactor and the'output of the first am plifi'er stage is solved. The impedance matchingproblem here is precisely the same impedance matching problem discussed with'regard to the circuit of FIGURE 4 and therefore this discussion is not repeated. 7 V

inspection of the circuit illustrated in FIGURE 9 shows'that' the magnetic amplifiers are connected tobe supplied from the transformer as wasdiscuss'ed with respect to the circuitof FIGURE 8 and also the reset'and main reactor circuit of the first amplifier stage is' identicalto that described with respect) the circuit of FIGURE 8 with the exception thatthe second stage reset impedance 'isconnected tola tap 106 on the second stage mainreactance winding 97. Thus the load circuit'of'thef first amplifier stage includes only a portion or thesecond' stage main reactance winding 97.

The main reactance circuit of the second stage may 93 through the load device '14; saturating rectifier 10S; secondstage main reactance "winding 97 and bacli tothe lower reactance voltage supply terminal 94. It will'be' noted that the second stage saturating rectifier infth'e circuit of FIGURE 9 is reversed with respect to the corresponding saturating rectifier in the circuit of FIGURE 8 and therefore the'load current in the second stage of this magnetic amplifier flows down in the directiori"labeled"Load Current. In view of thi'sfact the loadfcurrent for both stages of the magnetic amplifier fl'c'iwrduring the same half cycle of the reactance supply voltage. In order to' render this circuit operative a bias mustbe applied to the second stage reactor core menibr98f "in? such a manner as to completely reset thislcore once each half cycle. This biasin'g'circuit includes abiasin'g ir'nped ance107connected in series with themai n re aetancje winding97 and a biasing voltage, which may be ofthe' di'rect current type," is applied 'to this circuit between the biasing voltage"terminals '108and 109. p g Inordei' to provide control 'of'the o'utput of ,the ond amplifier stage from the first amplifier stage the output of the first stage must be such as to drive the seco'ndsta'ge in varying degrees out'of reset; thedegree.

being determined by the output of the first stage. The manner in which this function is accomplished is described belowt Assume that the first stage amplifier'is not reset and that the upper reactance supply terminal 93 is positive. Since the first stage amplifier is not' reset it will start toconduct early iri the cycle. Since the second stage amplifier is fully reset by the bias voltage, the

the second stage main reactance winding 97. The magnitude of this potential is determined by the potential applied at the'tap 10 6a nd the percentage of the main control signal applied to the first stageamplifier may be used to control the relatively high power output from the second amplifier stage. I i

The single sided magnetic amplifier illustrated in FIG- URE is provided specifically to obtain a circuit which may be utilized as a voltage and/ or frequency reference circuit. As in the single winding amplifier circuits described previously, a reactor is provided which has a main reactance winding 11% wound on a magnetic core member 111. The main reactance winding is preferably provided with a number of taps 112. The main reactance circuit includes the main reactor winding 110, a saturating rectifier 113, and a load impedance device 14 (connected between load terminals 15 and 16) connected in series with each other and across reactance supply voltage terminals 114 and 115.

In order to provide a main reactance supply voltage a transformer 116 is provided with a primary winding 117 connected to receive an alternating current voltage and a secondary winding 118 connected to the reactor supply voltage terrninals 114 and 115. Reset for the circuit is provided by means of a reset impedance 119 connected between the lower reactance voltage supply terminal 115 and a tap on the main reactance winding 110. Thus when the upper reactance voltage supply terminal 114 is positive flow current flows in a clock-wise direction around the main reactance circuit as shown by the arrow labeled Load Current. On the opposite half cycle (the reset half cycle) the saturating rectifier 113 blocks current flow through this circuit. However, on this half cycle a reset current path is provided from the lower reactance voltage supply terminal 115 through the reset impedance 119, the tapped portion of the main reactance winding 110, to the upper reactance voltage supply terminal 114. It will be recognized that this reset current flows through the main reactance winding 110 in a direction to reset the magnetic core member 111. Since the degree of core reset is determined by the energy supplied to the core member 111 during the reset half cycle,

the value of the reset impedance 119 and the percentage of the main reactance winding 110 included in the reset circuit may be adiusted to give the desired voltage across the load device 14.

It has been found that by careful selection of the tap position on the main reactance winding 110 and the magnitude of the reset impedance 119 the voltage drop across the load device may be made relatively insensitive to supply voltage and frequency over a relatively wide range. It has been found that in general the reset circuit should encompass about ninety percent of the reactorwinding 110. This is explained by the fact that once the degree of reset is selected, a'change in magnitude of applied voltage in one direction causes the degree of reset to change in the same direction and a change of supply voltage frequency simply shifts the reset point in a direction which tends to maintain the periods of current flow through the load occurring at a constant rate. For example, if the magnitude of the supply voltage increases the degree of reset increases. The reverse is true if the magnitude of the supply voltage decreases. If the frequency of the supply voltage increases (the magnitude remaining the same) the reset current will increase faster due to the steeper voltage wave front of the applied reset voltage thus tending to reset the core to a greater degree thereby causing the amplifier to fire later in the load current cycle and thus tending to keep the rate of occurrence of the periods of conduction constant regardless'of the frequency change. The reverse is true if the frequency of the supply voltage decreases.

A full wave frequency and/o voltage reference is illustrated in FIGURE 11. The upper half of this circuit is identical to the circuit illustrated in FIGURE 10 and operates in exactly the same manner as was described with respect to the circuit of FIGURE 10. The corresponding components in the two circuits are given the same reference numerals. A second single sided amplifier circuit is provided in order to provide full wave operation, the second circuit includes a second main reactance winding 120 wound on a saturable core member 127 and having taps 121 thereon and a second saturating rectifier 122 connected in series with each other and the load device 14. Power for the full wave circuit is provided by connecting a transformer 123 having a center tap secondary winding 124 and a primary winding 125 to receive a source of alternating voltage and connecting the upper half of its center tapped secondary winding to supply the reactor voltage supply terminals 114 and and the lower half of its secondary winding between lower reactor voltage supply terminals 115 and 128 to supply the main reactance voltage for the lower half of the full wave circuit. The saturating rectifiers 113 and 122 for the two halves of the full wave circuit are oppositely poled so that a load current will fiow through the load device 14 in the direction of the arrow labeled Load Current from one each half of the circuit on the opposite half cycles. A reset impedance 126 is connected between the taps 121 on the lower main reactor winding and the middle reactance voltage supply terminal 115 to provide a reset current through a portion of the main reactance winding 120 in the direction shown by the arrow labeled Reset Current on the reset half cycle for the lower half of the full wave circuit. Thus it will be seen that the upper half of the full wave circuit provides load current during the half cycle when the lower half of the circuit is being reset and vice versa.

Since each half of the full wave circuit acts as a voltage and frequency reference as described with respect to the single sided circuit of FIGURE 10 it will be apparent that combining the two circuits as illustrated in FIGURE 11 provides a full wave frequency and voltage reference.

While particular embodiments of this invention have been shown it will, of course, be understood that the invention is not limited thereto since many modifications both in the circuit arrangements and in the instrumentalities employed may be made. It is contemplated that the appended claims will cover any such modifications as fall within the true spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A push-pull saturable core impedance device comprising a first core of magnetic material, a single conducting main reactor winding on said first core, means to alternately supply said main winding with a reactor voltage of one polarity from one voltage source and a reset voltage of opposite polarity from a second voltage source, a second core of magnetic material, a single conducting main reactor winding on said second core, means to alternately supply said main winding on said second core with a reactor voltage from one voltage source and a reset voltage of opposite polarity from another voltage source, a pair of load terminals for connection to an electric load device connected in series with both of said main reactor windings and their respective reactor voltage sources in such a manner that the voltage developed across said terminals by each circuit due to said reactor voltages is in an opposite sense.

2. A push-pull saturable core impedance device comprising a transformer having a tapped secondary winding, a pair of output terminals, a pair of individual magnetic core members, a single conducting main winding on each of said individual magnetic core members, each of said single conducting main windings connected from an opposite side of said secondary winding to one of said output terminals, the remaining output terminal being connected to the tap of said secondary winding, separate .similarly poled unidirectional conducting devices conspasm input terminals, one of said reset terminalsbeing connected to the tap of said secondary winding, at least a pair of reset impedances each connected to the other reset voltage terminal andto an opposite reactor main in such a manner thatjtwo reset series circuits are provided-each of which includes one of said reset impedances and at least a portion of onset said single main reactor windings whereby a current is produced in each-of said'serics reset circuits by the reset voltage to provide magnetic reset for said core members.

3. A push-pull saturable core impedance device comprising a transformer having a tapped secondary winding, a pair of output terminals, a pair of individual magnetic core members, a single conducting main winding on each or said individual magnetic core members, each of said single conductingmain windings connected from an opposite side of said secondary windingto one of said output terminals, the remaining output terminal being connected to the tap of said secondary winding, separate sirnilarly poled unidirectional conducting devices connected between each main winding'and said one output terminal whereby said main windings tend to conduct current simultaneously, at least one pair of reset voltage input terminals, the remaining one of said reset voltage terminals being connected to said one output terminal, at

least a pair of reset impedances each connected to the other reset voltage terminal and to an opposite reactor main winding circuit in such a manner that two series reset series circuits are provided each of which includes one of said reset impedances and atleast a portion of one of said single main reactor windings whereby a current is produced in each of said series reset circuits by the reset voltage to provide magnetic reset for said core members. r

4. A push-pull saturable core impedance device comprising a transformer having a tapped secondary winding, a pair of output terminals, a pair of individual magnetic core members, a single conducting main winding on each of said individual magnetic core members, each of said single conducting main windings connected from an opposite side of said secondary winding to one of said output terminals, the remaining output terminal being connected to the tap of said secondary winding, separate similarly poled unidirectional conducting devices connected between each main winding and said one output terminal whereby said, main windings tend to conduct current simultaneously, at least one pair of reset voltage input terminalsflihe remaining one of said reset voltage terminals being connected to said one output terminal, at least a pair of reset impedances each connected to the other reset voltage terminal and to an opposite reactor I main winding circuit in such a manner that two series reset series circuits are provided each of which includes said transformer, individual series reset circuits for each of said magnetic core members, each of said series reset circuits including an individual reset impedance and at leasta portion of a single conducting main winding, said individual reset circuits being connected to receive the voltage developed across an opposite half of said tapped secondary winding.

6. Afsaturable core impedance devicecomprisinga core of saturable magnetic material having a thereon, a load circuit for connection across a first voltage source, said load circuit including a unidirectional conducting device and said winding, and a reset circuit for connection across ya second voltage source, said reset, circuit being connected to said load circuit in parallel with. said winding and in series with said 1midirectional conducting device relative to said first voltage source whereby reset current flows to said winding during non-conducting periods of said load circuit without passing through said first voltage source. I

7. A saturable core impedance device comprising a core of saturable magnetic material having a winding thereon, a load circuit tor connection across a first alternating voltage source, said load circuit including a first unidirectional device and said winding, and a reset circuit for connection across a second altemating voltage source, said reset circuit including a second unidirectional conducting device and being connected to said load circuit in parallel with said winding and in series with said first unidirectional conducting device, said second unidrectional device being polarized to. deliver reset current to said winding only during non-conducting periods of said load circuit, said reset current being blocked a by said first unidirectional conducting device from passing through said first voltage source.

, 8. A saturable core impedance device comprising'a core of saturable magnetic material having a winding thereon, means for developing two alternating voltagesof like frequency, a load circuit including a first unidirectional device and said winding connected to receive one of said voltages and a reset circuit connected to receive the other of said voltages, said reset circuit including o a reset impedance and a second unidirectional conducting one of said reset impedances; and at least a portion of one of said single main reactor windings whereby a current is produced in each of said series reset circuits by the reset voltage to provide magnetic reset for said core members, and separate biasing voltages connected across at least a portion of each single conducting main winding whereby the initial condition of said core members is set.

5. A push-pull saturable core impedance device comprising a transformer having a tapped secondary windings tend to conduct current on opposite half cycles of an alternating voltage across the secondary winding of device and being connected to said load circuit in parallel with said winding and in series with first unidirectional conducting device, said first and second'unidirectional conducting devices being similarly poled relative to said one voltage whereby reset current flows through said winding during non-conducting periods of said load circuit in a direction opposite to load current and without passing through said one voltage source. 9. A saturable core impedance device comprising core of saturable magnetic material having a winding thereon, a load circuit including a first unidirectional conducting device and a first pair of input terminals for connection to a first alternating voltage source, and a reset circuit including a second unidirectional conducting device and a second pair of input terminals for connection to a second alternating voltage source, said reset circuit being connected to said load circuit in parallel with said winding and in series with both said first unidirectional conducting device and said first input terminals, said unidirectional conducting devices being polarized relative to one another alternately to deliver current to said winding in oppositedirections. 7

10. A saturable core impedance device comprising a core of saturable magnetic material having a winding thereon, a load circuit for connection across a first alternating voltage source, said load circuit including a first unidirectional conducting device and said winding, a reset circuit for connection across a second alternating voltage source, said reset circuit including a second unidirectional conducting device and being connected to said load circuit in parallel with said winding and in series with said first unidirectional conducting device whereby reset current flows through said winding in a direction opposite to load 19 current therein during non-conducting periods of said load circuit without passing through said first voltage source, and means connected in parallel with at least a portion of said winding for supplying a biasing voltage across said Winding portion.

11. A saturable core impedance device comprising a core of saturable magnetic material having a winding thereon; a load circuit including a first unidirectional conducting device, said winding, a pair of output load terminals, and a first pair of input terminals; and a reset circuit including a second unidirectional conducting device, a reset impedance and a second pair of input terminals connected to said load circuit in parallel with said winding and said output terminals and in'series with said first unidirectional conducting device and said first input terminals; said unidirectional conducting devices being polarized alternately to deliver current to said Winding in opposite directions from alternating voltages supplied to said input terminals.

References Cited in the file of this patent UNITED STATES PATENTS 2,683,853 Logan July 13,1954 2,747,109 Montner May 22; 1956 2,773,133 Dunnet Dec. 4, 1956 2,783,315 Ramey Feb. 26, 1957 2,810,519 Creusere Oct. 22, 1957 2,840,778 Clarke June 24, 1958 FOREIGN PATENTS 1,112,349 France Nov. 9, 1955 OTHER REFERENCES Publication: Flux Preset High-Speed Magnetic Amplifiers by C. B. House A.I.E.E. Transactions, vol. 72, part 1, 1953, pages 728 to 735. 

